Parents can hardly influence the personality of their children. Decades of research show that the most important characteristics of humans are determined from birth - says the behavioral geneticist Robert Plomin.
Anyone raising children nowadays has a strenuous task ahead of them. Many parents believe that they are completely responsible for how their offspring develops: how good their children are at school; if they grow up happy and contented; how sociable and friendly they become. The good news for those who suffer from this comprehensive responsibility: that is not true. True, parents are incredibly important to the lives of their children. At the same time, however, they have little influence on their personal development.
Instead, the parents' greatest gift to their children is their genotype. For many people, that's hard to believe. Parents have a strong belief that their education is a crucial factor in the future lives of their children. They feed them, they help them learn to read and write; they encourage shy children or make them practice an instrument. Why else should parents buy parenting guides? Why are they constantly being told how to do it right and fearing the fear that they might do it wrong? Now, the influence of parents in some areas can not be denied - who does not learn manners at home, it will have trouble throughout life. However, in terms of personality traits such as intelligence, shyness or musicality, the parent influence is enormously overestimated.
The reasons for this misjudgment lie back over a hundred years. When psychology became established as a science at the beginning of the twentieth century, it placed the impact of the environment, especially that of its parents, as the formative force of human behavior at the center of its theories. The doctrine of "environmentalism" - we are what we have learned - dominated psychological thinking for decades. Already with Freud the family environment was considered as the key factor of our mental development. Schizophrenia, for example, was understood as a consequence of maternal misconduct in the first years of childhood of children.
It was not until the 1960s that geneticists began to revise this explanation of human behavioral differences. In fact, mental traits and illnesses accumulate in families. But is that the family environment, so the education? Little by little, researchers questioned whether genetic causes are responsible for these similarities in families. After all, the inheritance of children is 50 percent identical to that of their parents and siblings.
Over the past four decades, scientists have been studying specific relationships to accurately measure the effects of genes and the environment-families with twins or twins and those with adoptive children. For example, they compared how identical twin pairs (genetically 100 percent identical) differ from dizygotic pairs (genetically identical to 50 percent). Equally meaningful are such surveys of identical twins who grew up in different families after birth. Thousands of these and similar studies involving many thousands of pairs of twins have produced vast amounts of results, all of which have one message: they show the massive influence of genes on all of the characteristics that distinguish us humans. That is, the physical and psychological differences between individuals - in terms of height, intelligence, mental health, or personality traits such as openness, motivation, or self-control are, to a large extent, caused by hereditary differences in our DNA.
This is particularly evident in diseases: Whether children develop schizophrenia or bipolar disorder depends to 80 percent on what they inherit from their parents. In hereditary traits hereditary influence is less, but across all mental traits he determines over half of the differences.
The results of these studies have once again been confirmed in a meta-analysis by scientists around Peter Visscher and Danielle Posthuma in 2015, which included more than 2,700 publications with more than 14,000 pairs of twins. In addition, so-called genome-wide association studies have for ten years provided evidence of the heritability of many human characteristics. For example, since they have identified the many sites in the genome that are responsible for the heritability of a particular property, for example, since the publication of the largest association study so far, we know more than 1200 locations in the genome a few weeks ago, which correlate with differences in educational success and IQ. The result of 40 years of twin studies is often replicated and secured: at least half of our genetic make-up determines how we differ from others in our most important traits.
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